One unifying element of this program project is the use of Mycoplasma pulmonis-infected mice and rats as a model of chronic airway inflammation. All four projects will use this model to different extents in the proposed research. A small animal core will be established to serve two main functions: (i) to standardize M. pulmonis infection procedures and the handling of pathogen-free and infected mice and rats; and (ii) to develop, optimize and implement genotyping procedures to identify mutant mice. The core staff will establish virulent stocks of M. pulmonis. These stocks will be tested and used in all future experiments for program investigators in order to ensure reproducible results and to minimize variability. The core staff will be responsible for monitoring of pathogen-free and infected animals in the barrier facility, including the routine measurement of body weight, and periodic serological analyses. The core staff will also assist with some aspects of tissue harvesting, for example, bronchoalveolar lavage, flow cytometry, and tissue removal and fixation. Lastly, the core will use standardized flow cytometric, DNA preparation and polymerase chain reaction procedures to genotype mice from the various mutant colonies that will be used in the four projects. Centralizing infection and genotyping procedures will avoid unnecessary replication of resources in the four projects. It will also ensure that common procedures are used by all of the groups and will, therefore, facilitate the exchange of information and foster collaborative interactions.